Thermal controlled disposable unit heating apparatus

ABSTRACT

Heating apparatus for synthetic yarn processing comprising a pin or plate heater having a passive portion for attachment to a machine to provide and maintain predetermined alignment for a load contacting element of a removable and replaceable active portion. The thin load contacting element carries a thin etched foil heater and intimate resistance sensor bonded to its inner surface and is equipped with electrical leads to comprise the disposable active portion. The passive portion further thermally isolates the active portion to ensure high efficiency in transferring heat to the yarn load. Fast response inexpensive metals serve as the load contacting element so the compact low mass foil heater requires less power, responds quicker, and weighs and costs less than conventional yarn heaters.

United States Patent Leitner et al.

1 51 May 30, 1972 [54] THERMAL CONTROLLED DISPOSABLE UNIT HEATINGAPPARATUS [72] Inventors: Frank W. Leitner; Clayton 0. Miller, both ofCharlotte, N.C. 1

[73] Assignee: Coltron Industries, Inc., Charlotte, NC.

[22] Filed: Nov. 18, 1969 [21] App]. No.: 877,654

s21 U.S.Cl .....219 469,219/536,219 542 511 1111.01 ..B21b27 04 5sFieldoiSearch ..219/318,351,403,447,469, 219/463, 536, 542, 470, 471,543, 388

[56] References Cited UNITED STATES PATENTS 2,870,312 1/1959 Westervelt..219 543 3,414,711 12/1968 Guyetetal ...219/470x 3,417,226 12/1968Thomiszer.. ...2l9/388X 3,296,418 6/1967 Johnson ..219/469 3,484,58112/1969 Bliss ..219/469 Primary Examiner-Bemard A. Gilheany AssistantExaminer-F. E. Bell Attorney-Wilfred G. Caldwell ABSTRACT Heatingapparatus for synthetic yarn processing comprising a pin or plate heaterhaving a passive portion for attachment to a machine to provide andmaintain predetermined alignment for a load contacting element of aremovable and replaceable active portion. The thin load contactingelement carries a thin etched foil heater and intimate resistance sensorbonded to its inner surface and is equipped with electrical leads tocomprise the disposableactive portion. The passive portion furtherthermally isolates the active portion to ensure high efficiency intransferring heat to the yarn load. Fast response inexpensive metalsserve as the load contacting element so the compact low mass foil heaterrequires less power, responds quicker, and weighs and costs less thanconventional yarn heaters.

17 Claims, 10 Drawing Figures Patented May 30, 1972 3 Sheets-Sheet 2INVENTORS CLAYTON Q MILLER FRANK W. LEITNER BY M g (M ATTORNEY PatentedMay 30, 1972 3,666,922

3 Sheets-Sheet 5 INVENTORS CLAYTON O. MILLER FRANK W LEITNER BY MW WATTORNEY THERMAL CONTROLLED DISPOSABLE UNIT HEATING APPARATUS Thepresent invention relates to controlled heater apparatus in general and,in particular, to controlled heating surfaces for synthetic yarnprocessing, to household appliances or to other applications wheretemperature control is the significant requirement, but wherein'it isdesirable to permit replacement of the active heater portion withoutdisturbing the thermal control characteristics of the system.

The invention will be explained in connection with the illustratedapplication thereof to industrial pin or plate heaters; it beingunderstood that various other or different shaped apparatus includingrotating roll heaters, drum heaters, motorized roll heaters, and heatedgodets, as well as steam or non-steam irons may be made incorporatingthe principles herein taught.

In a typical installation, up to 144 heaters may be employed on a givenmachine or at a single location and, of course, even hundreds andthousands may be used in a single factory. With the. ever increasingcost of labor, it can be readily appreciated that in dealing with suchmagnitudes the disposable element or unit approach is almost mandatoryto financial survival.

The present invention proposes the rapid disassembly of the apparatusthrough the release of a single fastener, which may be of a common typefor all models, to remove and replace the active or disposable unitwithout disturbing mechanical alignment or thermal controlcharacteristics of the repaired heater.

In the usual case, the active unit will comprise the load supporting orwearing surface, a heating element and one or more sensors, theelectrical wiring or cable, and the connector for the wires of thecable. The inactive unit will include the mounting structure for theactive elements which mounting structure maintains intact the mechanicalalignment with the load, such that the new wearing surface assumes thelocation and configuration of the one replaced without requiring anyadjustments. 1 I I The heating elements are preferably of the typedescribed in copending U. S. application, Ser. No. 779,778 entitledLogical Control For Discretely Metering Energy To Thermal SystemsIncorporating Apparatus and Methods For Simulating Time RelatedTemperatures" filed Nov. 29, 1968 by Frank W. Leitner and Bobby B.Childress and assigned to Coltron Industries, Incorporated. Theseheaters are characterized by extreme thinness as they usually compriseetched heater elements in thermoplastic materials with one or moresensing elements of the resistance type being in intimate relation withthe heater elements.

Such heaters may be used with very thin, relatively inexpensivematerials to comprise a much improved pin or plate heater compatible tohigh speed control from on-off type energization, with suitable controlsalso being depicted in the above identified application.

In the present pin heater, the load contacting surface is a cylinderhaving affixed to its interior the'thin heater and sensor. The passiveportion thermally isolates and supports the cylinder in a given positionand orientation for cooperation with other machine components inefiecting drawing, twisting, draw-twisting, and etc..

By way of example, the present pin heater is compared to conventionalpin heaters A and B in the following table:

' Pin Pin Present Heater A Heater B O.D. 2'' 2" 2" Length 2.125 2.125"2.125 Wall Thickness .059" .375" 0.375" Material Steel Aluminum BrassRelative Thermal Capacitance l 2.1 5.7

Wattage I50 200 220 Time to elevate from 1 25C to 175C (secs) 72 I62 270Relative Response Time (secs) 1 2.25 3.75

efficiency because of low losses, and enables overall less powerrequirements because of less and better suited materials and moreefiicient interrelation or cooperation of the elements in the compactheater unit.

The invention is also depicted and described hereinafter in connectionwith its application to a plate heater whereinthe active portionincludes the same elements with the load surface or wearing surfacebeing an elongated strip that is arcuate but not cylindrical and themounting structure being slightly more elaborate than that necessary toa pin heater. However, in both types of heaters, it will be noted thatthermal control is inherently built into the mounting structure toisolate the wearing or load surface and heating and sensing element fromundesirable heat loss while improving the efficiency of the heattransfer to the load. In both cases, the heating units are isolated byemploying supporting members of low thermal conductivity materials andby providingair gaps or dead air spaces infurther'insulating relationthereto. Thus, the elongated, relatively narrow work surface for theplate heater is isolated by longitudinal air gaps from the mountingstructure. The present foil heater element permits the entire heatingunit to be quite thin and, thus, heat does not flow readily along thestrip length to be lost at the ends, nor across the strip width.

The described plate heater improves over conventional plate heaters Aand B as shown in the table below:

Deten'nined by thermal watts/thermal capacitance ratio and efficiency ofthermal coupling.

With the foregoing in mind, it is among the objects of the invention toprovide an improved heating apparatus incorporating a readily removableactive unit for replacement purposes.

Another object of. the invention is the provision of such a heaterapparatus utilizing a thin wearing or load contacting surface and a thinheating element bonded thereto.

A further object of the invention is the provision of such apparatus invarious types all adapted for replacement of the active unit through theuse of a single fastener.

A. still further object is the provision of such heating apparatuscapable of incorporating relatively inexpensive thin material for fasterthermal response than heretofore available.

Another object of the invention is the provision of thermal controlapparatus wherein each heating unit incorporates an active and a passivepart and wherein the passive part is the mount or support for the activepart and remains connected to a machine or the like while permittingready replacement of I the active portion without disturbing of anyalignment.

The invention will be better understood from the reading of thefollowing detailed description, when taken in the light of theaccompanying drawings wherein:

FIG. 1 is a perspective view of the new pin heater;

FIG. 2 shows, in perspective, the active or replaceable portion of theheater ofFIG. l;

' FIG. 3 is a view primarily in cross section of the heater of FIG. 1;

FIG. 4 is a view in end elevation of the heater of FIG. 1', FIG. 5 is anend view of the connector of FIG. 1;

FIG. 6;

FIG. 9 is a view of the other end of the heater of FIG. 6 showingprovisions to provide ready disassembly; and

FIG. 10 is a view in perspective of the active unit of the heater ofFIG. 6.

In FIG. 1, a fully assembled pin heater 11 is shown ready for mountingto a machine panel 41 (FIG. 3). It comprises a load contacting surfaceor body 13 mounted to a frame 15, in turn adapted to be secured to amachine or the like by means of stud screw 21.

The cylindrical heater body is secured to circular frame 15 by means ofa screw 23 fastening end plate 25 against the load surface cylinder 13,and in turn connected to coupling nut 45 (see FIG. 3).

In FIG. 1, a cable 19 brings out the electrical leads 35 to connector 17by way of slot 29 in frame 15, with the cable 19 being retained in theslot 29 by a compressible or a non-compressible bushing or grommet 27. I

Referring now collectively to FIGS. 1 through 5, it may be seen that theactive or replaceable unit 31 of FIG. 2 comprises the load contactingsurface or cylinder 13, an inner heater and sensor means 33, electricalleads 35, cable 19, grommet 27, and connector 17. Unit 33 comprises oneor more flexible foil etched heater or heaters and an intimate sensor orsensors all in thermoplastic material bonded or vulcanized to the innerwall or side of the cylinder or load contacting means 13 and' the foilheater and sensor leads 35 are brought out to pins such as 37 (FIG. 5)of connector 17. Thus, it may be appreciated that this structure admitsof mass production techniques at the factory at less cost than thedisposable unit 31 could be returned and repaired. The units 31, thenmay all exhibit the same thermal characteristics so substitutions may bemade without adjustments.

A feature of the invention resides in the provision of the singlefastener 23 of the screw type, inserted and removed through the use ofan Allen wrench, which serves as the sole connection for securing theactive portion 31 to the inactive frame or mounting portion. It shouldbe apparent that base 15 and set screw 21 affixed therethrough by theprovision of nut 43 and inner coupling nut 45 are maintained in a fixedposition of exact alignment with the machine panel or wall 41 (FIG. 3)regardless of whether the active unit 31 is present or not. Thus, anynumber of units 31 may be used as replacements and still present thesame alignment of cylinder or surface 13 with wall 41, it being apparentthat all other cooperating apparatus (not shown) is also aligned to wall41. Frequently the cylinder 13'is to have an exact mutual relation to aseparator roll or the like (not shown) of for-example -l0. Then theinadvertent cocking of a replacement cylinder 13 as much as one degreecould change the thread path and cause it to pile up. Thus, thepreservation of alignment is quite important.

It will be noted that cable 19 carries the grommet 27 which is free toslide out of the notch or slot 29 of frame 15. It should be mentionedthat a nylon sleeve may be substituted for rubber grommet 27 andordinarily a nylon string is knotted about cable 19 or a bulge formedthereon just below grommet 27 to eliminate any inadvertent strain onelectrical leads 35.

When the load carrying sleeve or cylinder 13 is secured about a shoulderof base 15, a notch (not shown) in the inner end of sleeve 13 isprovided to receive the stud or 45 degree angle projection 49 tore-enforce the union. It similarly will be noted that a notch 39 inconnector 17 serves to insure that when the correct wires 35 areconnected to the correct pins 37, the two sensing leads and the twoheater terminals will be correctly located for a pluggable connection toother equipment.

It will also be appreciated that the head of screw 23 fits thecountersink 47 in end cap 25, and the end cap has its edge bevelled ortapered at 35.

Considering now the structure described as an efficient pin heater, itwill be noted that the wall 13 may be of thin, inexpensive steel of theorder of 0.059 inches thick having bonded or vulcanized thereto a heatersensor unit of a few thousands (e.g. 13 or the like) of an inch thick.Thus, initially the heat path is directed through the surface 13 to theload, which normally would comprise synthetic strands wrapped aboutcylinder 13. The central or core region within the heating element 33 isa dead air space and the supporting structure is low thermalconductivity material, preferably plastic, for the base 15 and the endcap 25. Therefor, a highly efficient pin heater with -fast responseperformance, low wattage requirements and duplicatable characteristicsfrom active element to active element is presented.

FIGS. 6 through 10 depict a plate heater 51 incorporating the samedesirable principles for providing a high efiiciency disposable elementheating apparatus. The base or frame 53 may comprise an inexpensiveextruded section-of aluminum channel or the like having an upperlongitudinal slot to accommodate the load carrying surface 55 (which isthe only surface subject to wear) freely between the spaced apart sidearms 55.

End caps 57 and 61 are provided to close the frame or channel 53 withendears 59 and 63 extending outwardly to provide ingress and egressguides for the textile fibers to be heated by surface 55. The end capsor pieces 57 and 61 also provide recesses for receiving the ends ofstrip 55, which strip is bowed outwardly in the middle by a plasticupright post 93 (FIG. 7). This configuration ensures that good contactis madewith the strands for providing the set point temperatures.

The heater plate assembly 5 permits removal of the active unit 101(shown in FIG. 10) by removal of the screw 81 and end cap 57. It shouldbe noted that screw 81 may include an Allen wrench receiving head in themanner of the pin heater assembly 1 1 of FIG. 1 in order that bothheaters may be disassembled and their active portions replaced utilizingthe same tool. Otherwise, the end cap 61 is more permanently secured tothe channel or base frame 53 by screws 73 and 75 which are received inlugs, such as 83 and 85 (FIG. 7) molded into the low thermalconductivity material, e.g. plastic, of end cap 61.

It should be mentioned that, usually the plate heater 51 will be mountedin a vertical position, and the threaded screw holes 77, 77', 79, and79' are provided for mounting to a machine panel or the like. Also, itshould be pointed out that the side arms 55' are spaced apartsufficiently to leave air gap spacings 96 between the strip 55 and thearms for its entire length, thereby assuring that the only contact madewith the strip 55 by the frame 53 is through the plastic or low thermalconductivity materials of end caps 57 and 61 and biasing post 93, thelatter being secured to the bottom of base 53 by screw 95. Also, a rightangle bracket 87 is permanently secured to the bottom of frame 53 toreceive the screw or bolt 81 (FIG. 7).

In order to remove the cable 65 and connector 67, shown as of thefanning strip type, the channel 53 is slotted at four end locations,each shown closed by the rubber bushings or grommets 71, 71, 69, and 69.Thus, it is only necessary to remove the appropriate end cap, such as 57and slide cable 65 out the right slotted end of channel 53, along withthe strip 55 and combination heater and sensor backing 91 of the typeheretofore described. Replacement is made in the reverse order.

In FIG. 10, the active unit 101 is shown including the strip 55 withheater sensor 91, electrical leads 103, cable 65, grommet 69, andconnector strip 67. 104 is a second sensor for readout and is an ironconstant an thermocouple It should be noted that the connectors 17 forthe pin heater and 67 for the plate heater may be interchanged or mayboth be of the same type depending on the installation. Additionally, itmay be pointed out that the interior of channel 53 may be lined withfiberglass insulation or finished inside and out with white resistingcoating, even further to assist in the direction of heat from heater 91through strip 55. The strip 55 is well insulated from its support 53,and since it is a long thin strip(in one example, approximately 8 inchesby three-fourth inches) it will not conduct much heat lengthwise andthus end losses are minimized. Similarly, very little heat is conductedlaterally of strip 55. Also, strip 55 may comprise fast responsive andinexpensive material, such as steel, and being thin and having reducedlosses, the wattage requirements are considerably reduced in transferingthe heat to the load. The strip 55 is preferably finished by flamecoating.

In summary then, the active unit 101 is disposable because it can bemass produced reliably at the factory to the same specifications cheaperthan it can be repaired, particularly where inexpensive materials areemployed. The thinness of the strip substantially prevents lateral andlongitudinal losses and the bulk of the heat. is directed outwardly tothe load. This efficiency is further enhanced by the air and plasticinsulation otherwise bounding strip 55.

What is claimed is;

l. Stationary or non-rotating low thermal mass heating apparatus forfast response controlled heating of a load comprising in combination apassive unit and an active unit readily disconnectible therefrom; saidpassive unit comprising a frame and fastening means for securing theactive unit to the frame; said active unit comprising load supportingand contacting surface means, heater means for the surface meansdisposed against said means opposite the load contacting surface on itsinner side, resistive sensor means, and electrical lead-in means for theheater means and sensor means; said supporting surface means, heatermeans, and sensor means being inseparably bonded together.

2. The apparatus of claim 1 wherein said frame comprises an end piece oflow thermal conductivity adapted to mate with an end of the loadsupporting and contacting surface means to securethe latter to the framevia the fastening means.

3. The apparatus of claim 2 wherein the load supporting and contactingsurface means is arcuate and the heater means is arcuate in conformitythereto.

4. The apparatus of claim 3 wherein the frame comprises a furtherportion of low thermal conductivity adapted to receive the opposite endof the load supporting and contacting surface means and the framefurther provides air gap separation between it and the heater means.

S. The apparatus of claim 1 wherein said heating apparatus comprises apin heater for synthetic yarn; said load supporting and contactingsurface means comprises a cylinder for containing the heater meanstherein; and said frame comprises mounting means for securing it to amachine or the like in predetermined orientation and said frameorienting the cylinder to it and the machine whereby replacement of saidactive unit automatically orients the replacement cylinder in therequired orientation relative to the machine.

6. The apparatus of claim 5 wherein the frame comprises spaced apartportions of low thermal conductivity for receiving opposite ends of thecylinder; said fastening means securing the portions together to orientand hold the cylinder in predetermined position. v

7. The apparatus of claim 6 wherein one of said portions is slotted toits edge at one location to accommodate the electrical lead-in means;and further comprising means carried by the lead-in means for insertioninto and removal from the slotted location to permit replacement of theactive unit.

8. The apparatus of claim 1 wherein said heating apparatus comprises aplate heater for synthetic yarn; said load supporting and contactingsurface means comprises an elongated strip; said heater meanssubstantially conforming to the configuration of the strip and disposedon its inner side relative to the frame; and said frame being adapted tobe secured to a machine or like in predetermined orientation and saidframe orienting said strip to it and to the machine whereby replacementof said active unit automatically orients the replacement strip in therequired orientation relative to the machine.

9. The apparatus of claim 8 wherein the frame comprises spaced apartportions of low thermal conductivity for receiving opposite ends of thestrip, said fastening means securing the portions together to orient andto hold the strip in predetermined position.

10. The apparatus of claim 9 wherein the frame is slotted to its edge atone location to accommodate the electrical lead-in means; and furthercomprising means carried by the lead-in means for insertion into andremoval from the slotted location to permit replacement of the activeunit.

11. Heater apparatus capable of fast thermal response and the use ofdisposable components to supply controlled heat to a load, comprising incombination an active unit and a passive unit, said activeunitcomprising a heater body characterized by low thermal capacitance forcontact with the load on one side thereof, combination heating andresistive sensor means permanently affixed to the other side of theheater body and characterized by thinness of the order of less than amajor portiori of the thickness of the heater body, and electrical leadsfor the heating means; said passive unit comprising frame means foraligning and supporting the heater body, and means for releasing theheater body and fastening a replacement heater body in the alignment ofthe replaced heater body.

12. The heater apparatus of claim 11 wherein said frame means compriseelements of low thermal conductivity material for supporting the heaterbody at more than a single location and for otherwise isolating theheating means through air insulation. I

13. The heater apparatus of claim 12 wherein the heater body is arcuateand the heating means is arcuate in conformity thereto.

14. The heater apparatus of claim 13 comprising a pin heater for asynthetic yarn load; said heater body comprising a cylinder forcontaining the heating means; and said frame means being adapted to besecured to a machine or the like in predetermined alignment to establishalignment of the cylinder relative to the machine.

15. The apparatus of claim 13 comprising a plate heater for a syntheticyarn load; said heater body comprising an elongated strip; and saidframe means being adapted to be secured to a machine or the like inpredetermined alignment to establish alignment of the strip relative tothe machine.

16. Plate heater apparatus for the efficient heating of a load of movingsynthetic yarn comprising in combination a relatively thin, narrow, butelongated heater body of a material characterized by relatively fastthermal response time of the order of steel for contact along oneelongated surface thereof with the load; frame means of low thermalconductivity material for supporting the body by its ends and forproviding air gaps along the edges between said ends; heating andresistive sensing means permanently affixed to the opposite surface ofthe heater body and characterized by extreme thinness relative to thebody; electrical leads permanently connected to the heating and sensingmeans; and means for readily releasing the heater body, heating andresistive sensing means and electrical leads therefor from the framemeans to permit replacement thereof without otherwise disturbing theframe means.

17. The apparatus of claim 11 wherein said combination heating andresistive sensor means are substantially in the same plane when seen ina cross-section view taken through the heater body and combinationheating and resistive sensor means.

1. Stationary or non-rotating low thermal mass heating apparatus forfast response controlled heating of a load comprising in combination apassive unit and an active unit readily disconnectible therefrom; saidpassive unit comprising a frame and fastening means for securing theactive unit to the frame; said active unit comprising load supportingand contacting surface means, heater means for the surface meansdisposed against said means opposite the load contacting surface on itsinner side, resistive sensor means, and electrical lead-in means for theheater means and sensor means; said supporting surface means, heatermeans, and sensor means being inseparably bonded together.
 2. Theapparatus of claim 1 wherein said frame comprises an end piece of lowthermal conductivity adapted to mate with an end of the load supportingand contacting surface means to secure the latter to the frame via thefastening means.
 3. The apparatus of claim 2 wherein the load supportingand contacting surface means is arcuate and the heater means is arcuatein conformity thereto.
 4. The apparatus of claim 3 wherein the framecomprises a further portion of low thermal conductivity adapted toreceive the opposite end of the load supporting and contacting surfacemeans and the frame further provides air gap separation between it andthe heater means.
 5. The apparatus of claim 1 wherein said heatingapparatus comprises a pin heater for synthetic yarn; said loadsupporting and contacting surface means comprises a cylinder forcontaining the heater means therein; and said frame comprises mountingmeans for securing it to a machine or the like in predeterminedorientation and said frame orienting the cylinder to it and the machinewhereby replacement of said active unit automatically orients thereplacement cylinder in the required orientation relative to themachine.
 6. The apparatus of claim 5 wherein the frame comprises spacedapart portions of low thermal conductivity for receiving opposite endsof the cylinder; said fastening means securing the portions together toorient and hold the cylinder in predetermined position.
 7. The apparatusof claim 6 wherein one of said portions is slotted to its edge at onelocation to accommodate the electrical lead-in means; and furthercomprising means carried by the lead-in means for insertion into andremoval from the slotted location to permit replacement of the activeunit.
 8. The apparatus of claim 1 wherein said heating apparatuscomprises a plate heater for synthetic yarn; said load supporting andcontacting surface means comprises an elongated strip; said heater meanssubstantially conforming to the configuration of the strip and disposedon its inner side relative to the frame; and said frame being adapted tobe secured to a machine or like in predetermined orientation and saidframe orienting said strip to it and to the machine whereby replacementof said active unit automatically orients the replacement strip in therequired orientation relative to the machine.
 9. The apparatus of claim8 wherein the frame comprises spaced apart portions of low thermalconductivity for receiving opposite ends of the strip, said fasteningmeans securing the portions together to orient and to hold the strip inpredetermined position.
 10. The apparatus of claim 9 wherein the frameis slotted to its edge at one location to accommodate the electricallead-in means; and further comprising means carried by the lead-in meansfor insertion into and removal from the slotted location to permitreplacement of the active unit.
 11. Heater apparatus capable of fastthermal response and the use of disposable components to supplycontrolled heat to a load, comprising in combination an active unit anda passive unit, said active unit comprising a heater body characterizedby low thermal capacitance for contact with the load on one sidethereof, combination heating and resistive sensor means permanentlyaffixed to the other side of the heater body and characterized bythinness of the order of less than a major portion of the thickness ofthe heater body, and electrical leads for the heating means; saidpassive unit comprising frame means for aligning and supporting theheater body, and means for releasing the heater body and fastening areplacement heater body in the alignment of the replaced heater body.12. The heater apparatus of claim 11 wherein said frame means compriseelements of low thermal conductivity material for supporting the heaterbody at more than a single location and for otherwise isolating theheating means through air insulation.
 13. The heater apparatus of claim12 wherein the heater body is arcuate and the heating means is arcuatein conformity thereto.
 14. The heater apparatus of claim 13 compRising apin heater for a synthetic yarn load; said heater body comprising acylinder for containing the heating means; and said frame means beingadapted to be secured to a machine or the like in predeterminedalignment to establish alignment of the cylinder relative to themachine.
 15. The apparatus of claim 13 comprising a plate heater for asynthetic yarn load; said heater body comprising an elongated strip; andsaid frame means being adapted to be secured to a machine or the like inpredetermined alignment to establish alignment of the strip relative tothe machine.
 16. Plate heater apparatus for the efficient heating of aload of moving synthetic yarn comprising in combination a relativelythin, narrow, but elongated heater body of a material characterized byrelatively fast thermal response time of the order of steel for contactalong one elongated surface thereof with the load; frame means of lowthermal conductivity material for supporting the body by its ends andfor providing air gaps along the edges between said ends; heating andresistive sensing means permanently affixed to the opposite surface ofthe heater body and characterized by extreme thinness relative to thebody; electrical leads permanently connected to the heating and sensingmeans; and means for readily releasing the heater body, heating andresistive sensing means and electrical leads therefor from the framemeans to permit replacement thereof without otherwise disturbing theframe means.
 17. The apparatus of claim 11 wherein said combinationheating and resistive sensor means are substantially in the same planewhen seen in a cross-section view taken through the heater body andcombination heating and resistive sensor means.